Resilience, endurance, learning to overcome adversity, learning to overcome yourself, learning to be self-aware, thinking "differently". I could think of dozens of other reasons. No?
These sort of ideas are hard to evaluate definitively, but I do think it is plausible that mild depression had/to some extent may still have benefits. Of course certain traits can be taken too far though, and when viewed through that lens it is hard to understand how they could be beneficial at all. One could say a similar thing about Autism-like traits.
Literal survivor's bias. If you are depressed but not resilient, you kill yourself.
> learning to overcome adversity, learning to overcome yourself
Overcoming adversity requires doing something. Depression prevents that.
> learning to be self-aware
I wish.
> thinking "differently".
In what way?